In the prior art, cartons are erected from collapsed blanks by comparatively high speed machines such as shown in U.S. Pat. Nos. 3,763,750 and 3,828,659. After leaving the erecting machine, the bottom flaps of the erected cartons are folded and sealed by other apparatuses exemplified by U.S. Pat. Nos. 3,482,489; 3,620,138 and 3,902,406.
A serious problem arises as a result of the inability of the flap sealing apparatus or machine to process cartons at a sufficient speed to keep up with the output of the high speed carton erecting machine. As a result, additional sealing machinery must be employed at increased expense and loss of floor space or the erecting machinery must be shut down periodically to avoid carton pile-up. Thus, the prior art arrangements are not in the interest of good economy and continuous smooth and efficient manufacturing operation.
The objective of this invention is, therefore, to eliminate the above deficiencies of the prior art through the provision of apparatus in the nature of an addition to the customary high speed carton erecting machine which will be capable of sealing the bottom flaps of cartons as they are delivered by the erecting machine at the same speed as the delivery speed of the erecting machine, thus avoiding carton pile-up. The present invention accomplishes this objective by means of a very simple continuous motion apparatus and method which involves engaging each carton in succession at a carton squaring and lower flap folding station with continuously traveling carton flap compression units driven by endless conveyor means in predetermined spaced relation to achieve timing coordinated with the delivery of cartons from the erecting machine. The continuously moving compression units or rams travel with the empty cartons away from the squaring and flap folding station and apply flap sealing pressure to the bottoms of the cartons while they are moving on a conveyor support to a discharge station where the flap sealing operation has been completed following the application of pressure for a sufficient time. At this station, the continuously traveling compression units separate from the cartons and continue their movement to process oncoming erected cartons in the same manner. Glue is applied to the lower flaps of the cartons in advance of the carton squaring and flap folding station, or in a variant of the invention adjacent to an intermediate transfer and timing station where the lower flaps are folded during uninterrupted movement of the cartons.
Other features and advantages of the invention will become apparent during the course of the following detailed description.